WASHINGTON (CNN) -- A mandatory grounding of Air Force F-15s has been expanded to cover those flying combat missions over Afghanistan after a crash in Missouri last week, Air Force officials said Monday.

The Air Force grounded models of its F-15 fleet after the crash of an older model F-15C Friday.

The F-15Es in Afghanistan can fly only in emergency situations to protect U.S. and coalition troops in a battle, according to Maj. John Elolf, a spokesman for the U.S. Air Force Central Command.

Maj. Cristin Marposon, an Air Force spokeswoman, told The Associated Press the country's fleet of 676 F-15s, including mission critical jets, was grounded on November 3 for "airworthiness concerns" after the crash of an older model F-15C on Friday.

The cause of the crash is still under investigation, but Air Force officials said it was a structural failure and the plane broke apart in flight.

A spokeswoman for Boeing, the aircraft's manufacturer, told AP the company was cooperating with the Air Force but could not provide additional comment because of the pending investigation.

Col. Robert Leeker, commander of the 131st Fighter Wing, said Friday the plane had been among four planes split into pairs and were engaging in one-on-one training flights in which speeds of 400 to 450 mph are typical, according to AP.

A pilot, a 10-year veteran of the guard whose name and rank were not released, safely ejected from the aircraft when it crashed in Dent County, Missouri, AP reported. The pilot suffered a dislocated shoulder, a broken arm and minor cuts and bruises.

Now only "mission critical" F-15s will fly.

Pentagon officials said the U.S. Navy has had to move the only aircraft carrier in the region from the Persian Gulf to the North Arabian Sea to fill mission gaps for the F-15s.

Several dozen F/A-18 fighters from the aircraft carrier USS Enterprise will fly missions with other Air Force aircraft to fill mission gaps.

The F-15E Strike Eagle is an air-to-ground and air-to-air fighter, making it more versatile than other F-15 models, which are used for only air-to-air missions.

The Strike Eagle is used in Afghanistan in its air to ground role, dropping bombs on targets with its advanced sensors.

"The U.S. Air Force maintains assigned F-15E Strike Eagles on ground alert and will accomplish all assigned missions with a variety of fighter, attack and bomber aircraft, and unmanned aerial vehicles, under my command and control during this period," Lt. Gen. Gary L. North, commander of the U.S. Central Command's Combined Forces Air Component, said in a statement Monday.

The single-seat F-15C is one of the older models in the Air Force's fleet of 700 F-15s which entered service in 1979.

The Air Force's top aircraft, the stealthy F-22 Raptor, is newly operational for the air service and has not yet been deployed in combat.

The expensive F-22 will eventually be the main fighter jet for the Air Force, but budgetary restrictions on the plane have forced the Air Force to cut the number of planes it will have in the fleet.E-mail to a friend